LIHU'E, Kaua'i — Bruce Orth was sitting on his surfboard in 4- to 8-foot surf at Kalihiwai Bay yesterday when a shark came up and bit the left side of the board.

"I just started pounding him," said Orth, 51, of Kilauea. "I think I got two good punches in. I was just trying to push him off."

Fellow surfer Wayne Smith, 49, also of Kilauea, said the gray shark appeared to be about 2 feet longer than Orth's 8-foot board.

"He let out this yell — kind of a scream. The shark was between me and him. The view I had, it looked like it had him by the arm or shoulder," Smith said. It did not, and Orth was not injured.

The attack lasted just seconds, then the shark let go and disappeared. Both men said it was big and gray, but could not be sure of the species.

Orth thinks it could have been a tiger shark. He said the bite mark left an impression about 12 inches across.

Lifeguard Kalani Vierra of the county's Ocean Safety Bureau said the water at the bay was a little murky but not at all muddy, with onshore winds and choppy conditions. The county posted signs warning beachgoers to stay out of the water until further notice.

"They're out there, I know that, (but) I'm a lot more scared of riding a bicycle in highway traffic than surfing," Orth said.

The attack took place about nine miles from the Tunnels surf break near Ha'ena Beach Park, where 13-year-old surfer Bethany Hamilton lost an arm to a 14-foot tiger shark Oct. 31.